Linear Tape-Open (“LTO”) is a computer storage magnetic tape format developed as an alternative to the proprietary Digital Linear Tape (“DLT”) format. The LTO roadmap calls for successive increases in capacity and speed. Due to these targets and the need to maintain, and perhaps shrink, a small drive housing form-factor, printed circuit board real estate is becoming very valuable as the need to include additional components increases. Due to this, it is becoming challenging to fit various drive mechanisms, included in previous generation LTO drives, into newer designs.
Designing high bandwidth tracking servo systems, for use in LTO drives, presents the following technological challenges: high bandwidth amplifiers, faster sample rates for digital control algorithms, control of loop shaping to achieve robust and higher performance suppression capabilities, improved feedback sensors and high bandwidth actuators. Although each one of these is an important design or engineering task, the performance of the actuator basically limits the final tracking servo bandwidth. As a result, the actuator is often considered to be the most important requirement.
As discussed in more detail below, the claimed embodiments are directed to high bandwidth actuators. Some of the issues with high performance actuators are: minimizing moving mass, optimization of the working lateral range of motion and controlling the high order unwanted resonance frequencies above a minimum frequency that is determined based on the tracking servo bandwidth requirements.
In addition, drive form factors (for example LTO form factor requirements) and installation/mounting requirements are also a concern. Some computer industry requirements include the drive mounting configurations. For example, some computer manufactures specify a drive-mounting configuration requirement that the drive can be mounted on its lateral side or on its bottom side. The side-mounting configuration requires two sets of hole-patterns with a minimum screw length that will support the drive in a computer chassis. A typical screw length requirement is about 4 to 5 millimeters. In a LTO half-high drive (½ of the standard height of 3¼ inches) the pin threading mechanisms must be spaced away from the mounting screw. Thus, the actuator must fit between the pin threading mechanisms and the drive reel located in the back. The actuator must also fit in the limited space in the width dimension. Prior art actuator assemblies are typically not suitable for tape drives with smaller form factors where drive components are more tightly packed. In addition, some of the actuator configurations of the prior art force a lower 1st mode resonance frequency response at around 100 Hz. Generally, a lower 1st mode of the spring-mass system also results in a lower 2nd mode of resonance.
In view of the foregoing, a need exists in the art for a high bandwidth actuator that meets the above-described technological requirements.
The foregoing examples of the related art and limitations related therewith are intended to be illustrative and not exclusive. Other limitations of the related art will become apparent to those of skill in the art upon a reading of the specification and a study of the drawings.